1 files changed, 90 insertions, 0 deletions
diff --git a/venv/lib/python3.11/site-packages/litestar/channels/backends/asyncpg.py b/venv/lib/python3.11/site-packages/litestar/channels/backends/asyncpg.py
new file mode 100644
index 0000000..967b208
--- /dev/null
+++ b/venv/lib/python3.11/site-packages/litestar/channels/backends/asyncpg.py
@@ -0,0 +1,90 @@
+from __future__ import annotations
+
+import asyncio
+from contextlib import AsyncExitStack
+from functools import partial
+from typing import AsyncGenerator, Awaitable, Callable, Iterable, overload
+
+import asyncpg
+
+from litestar.channels import ChannelsBackend
+from litestar.exceptions import ImproperlyConfiguredException
+
+
+class AsyncPgChannelsBackend(ChannelsBackend):
+    _listener_conn: asyncpg.Connection
+
+    @overload
+    def __init__(self, dsn: str) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        *,
+        make_connection: Callable[[], Awaitable[asyncpg.Connection]],
+    ) -> None: ...
+
+    def __init__(
+        self,
+        dsn: str | None = None,
+        *,
+        make_connection: Callable[[], Awaitable[asyncpg.Connection]] | None = None,
+    ) -> None:
+        if not (dsn or make_connection):
+            raise ImproperlyConfiguredException("Need to specify dsn or make_connection")
+
+        self._subscribed_channels: set[str] = set()
+        self._exit_stack = AsyncExitStack()
+        self._connect = make_connection or partial(asyncpg.connect, dsn=dsn)
+        self._queue: asyncio.Queue[tuple[str, bytes]] | None = None
+
+    async def on_startup(self) -> None:
+        self._queue = asyncio.Queue()
+        self._listener_conn = await self._connect()
+
+    async def on_shutdown(self) -> None:
+        await self._listener_conn.close()
+        self._queue = None
+
+    async def publish(self, data: bytes, channels: Iterable[str]) -> None:
+        if self._queue is None:
+            raise RuntimeError("Backend not yet initialized. Did you forget to call on_startup?")
+
+        dec_data = data.decode("utf-8")
+
+        conn = await self._connect()
+        try:
+            for channel in channels:
+                await conn.execute("SELECT pg_notify($1, $2);", channel, dec_data)
+        finally:
+            await conn.close()
+
+    async def subscribe(self, channels: Iterable[str]) -> None:
+        for channel in set(channels) - self._subscribed_channels:
+            await self._listener_conn.add_listener(channel, self._listener)  # type: ignore[arg-type]
+            self._subscribed_channels.add(channel)
+
+    async def unsubscribe(self, channels: Iterable[str]) -> None:
+        for channel in channels:
+            await self._listener_conn.remove_listener(channel, self._listener)  # type: ignore[arg-type]
+        self._subscribed_channels = self._subscribed_channels - set(channels)
+
+    async def stream_events(self) -> AsyncGenerator[tuple[str, bytes], None]:
+        if self._queue is None:
+            raise RuntimeError("Backend not yet initialized. Did you forget to call on_startup?")
+
+        while True:
+            channel, message = await self._queue.get()
+            self._queue.task_done()
+            # an UNLISTEN may be in transit while we're getting here, so we double-check
+            # that we are actually supposed to deliver this message
+            if channel in self._subscribed_channels:
+                yield channel, message
+
+    async def get_history(self, channel: str, limit: int | None = None) -> list[bytes]:
+        raise NotImplementedError()
+
+    def _listener(self, /, connection: asyncpg.Connection, pid: int, channel: str, payload: object) -> None:
+        if not isinstance(payload, str):
+            raise RuntimeError("Invalid data received")
+        self._queue.put_nowait((channel, payload.encode("utf-8")))  # type: ignore[union-attr]